Controlling vitamin and flavor stability of dilute juice beverages is an ongoing concern among beverage manufacturers. It is important that beverages maintain their intended flavor characteristics and nutritional characteristics, even after prolonged periods of shelf storage.
One source of flavor degradation is microbial growth. Another source of flavor degradation is oxidation of certain unsaturated compounds. Additionally, oxidation can also be a cause of degradation of vitamin compounds. For instance, certain water soluble vitamins, oil soluble vitamins, flavor oils, and flavor essences can be degraded by oxidation if dissolved oxygen is present in the beverage container.
Microbial degradation can result from accidental inoculation of the beverage products during manufacturing or packaging. Food spoilage microorganisms can then rapidly proliferate by feeding on nutrients provided by the fruit juice component of the noncarbonated dilute juice beverages. Flavor degradation and vitamin degradation due to oxidation can occur when dissolved oxygen and a catalyst, such as metal ions, are present in the packaged beverage, or when the beverage package is relatively oxygen permeable, such as in the case of relatively inexpensive plastic packaging, such as high density polyethylene (HDPE) packages. Such plastic containers can provide a relatively poor barrier to oxygen, when compared to containers made of glass or metal. Oxygen passing through the container can cause oxidation of beverage ingredients which include water and oil soluble components, including vitamins and flavor components including flavor oils. This oxidation can result in the loss of vitamin content and the formation of undesirable flavors and/or odors.
Microbial stability in dilute beverage products can be provided to some extent by heat pasteurizing during packaging (hot packing) or by packaging under completely aseptic conditions (aseptic packaging). Special packaging constructions for providing a barrier between oxygen in the atmosphere and the beverage can also be used to reduce the amount of oxygen that enters the beverage over time. However, such processing or packaging methods are generally undesirable from a cost and complexity standpoint. Also, flexible containers made from polymeric materials, such as high density polyethylene, which have become more popular with consumers, should not be subjected to the pasteurization temperatures utilized during hot packing operations.
U.S. Pat. No. 5,431,940 to Calderas et al. discloses a beverage containing a polyphosphate and a preservative for beverage products that are to be stored at ambient temperatures for at least about 10 days without substantial microbial proliferation. One disadvantage associated with the polyphosphate disclosed in U.S. Pat. No. 5,431,940 is that, over time, the effectiveness of the polyphosphate as a chelating agent may be reduced. Without being limited by theory, it is believed that the chain length of the polyphosphate can be reduced over time, such as by hydrolysis.